| 摘要 |
PURPOSE: An adaptive type feed-forward linear amplifier is provided to materialize a feed-forward linear amplifier, which is the most superior in function of linear amplifiers and to control a linear loop of the feed-forward linear amplifier without using a filter. CONSTITUTION: The adaptive type feed-forward linear amplifier includes the first and second frequency synthesizers(PLL1,PLL2), a controller, the first, second and third signal generators(PLL1,PLL2,PLL3) and the first, second and third mixers. Two frequency synthesizers(PLL1,PLL2) generate the pilot signal. The information for controlling the frequency synthesizers is stored in a memorizing device of the controller. The first signal generator(PLL1) generates the first pilot signal and the second signal synthesizer(PLL2) generates the second pilot signal. And the third signal generator(PLL3) generates the local oscillator(LO) of the first, second and third mixers(Mixer1,2,3). At last the controller controls a phase shifter and the second variable attenuator for maintaining the first pilot signal size as the minimum detected through the second mixer and the second power detector. Thereby the linear function of the first loop of the feed-forward linear amplifier is maintained as the maximum.
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